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Multi Burst Envelopes - AJH Synths

Multi Burst Envelopes - AJH Synths

by Jason Czyeryk

One of the first modules I ever purchased was an AJH Synth’s Mini Mod VCF, and ever since I’ve been a fan of their modules. Their Mini Mod line [modeled after early Moog synths] is flexible and, of course, classic, and while the VCF came out a time when a Moog filter wasn’t available on every street corner as it is now, the Mini Mod line has since pushed itself out from its initial Moog-ish concept, and their Multi Burst Envelopes module is a great example of this. By the way, the VCF still rules.
Burst generating modules are already fun, but the AJH Multi Burst Envelopes [referred to as MBE from here on out] takes bursting to another level. Instead of just offering only the typical pulse wave bursting, MBE offers eight preconfigured attack/decay type envelope shapes, ranging from sine-y humps to descending ramps to, yes, pulses that are chosen via a rotary switch at the top. The envelope shapes can also be modulated by incoming and the CV amount determines which shape is selected. There are a couple of very helpful LEDs on MBE; one on the left for signaling when a burst sequence is occurring, and one on the right that shows the strength of each burst and lights up with each clock pulse.
There’s a BURSTS control for selecting the number of bursts per trigger [from 1 burst to 40], an internal LFO to set the rate of the bursting, a SLOPE function to determine whether or not the amplitude of the burst sequence ascends, descends, or maintains the maximum output for every burst, and a P-WIDTH [pulse width] control which determines the envelope times. The interplay between these parameters can be unusual, interesting, and extremely flexible. When I’m talking flexibility here, I mean that MBE is a sound designers dream. You can do the craziest ratcheting—with envelope shapes and not just pulses, which is more typical—make all manner of vintage [and modern, I suppose] video game sounds, create sirens of any nationality/country, wreak percussive havoc, and so much more. Melodic, percussive, drone-y, MBE has many occasions for use. These functions can all be CV controlled and when patched, the controls become attenuators for dialing in the right amount. In my testing it wasn’t all smooth sailing, and it was mostly due to my propensity for initially wanting to ignore a manual, but there are a couple of things to know when CVing MBE. First, the SLOPE and BURST amount can’t be changed once the burst sequence is running, and any changes made during that time will be implemented on the next trigger/cycle. In this way I found that in order to get certain things to happen, like an ascending, then descending melody, you had to patch wisely and thoughtfully—not such a bad thing, right? Conversely, P-WIDTH and the ENV shape can be changed while the burst sequence is running so you could start with a short burst in the beginning of a cycle and end with a long burst.
There are two inputs to get things going in a literal sense. The first is a TRIGGER input with a switch to toggle between ONE-SHOT or RETrigger modes and a button for manual triggering. ONE-SHOT plays through its burst sequence until the end before you’re able to retrigger it, and RETrigger mode allows for starting the sequence from the beginning no matter where in the sequence of bursts you are. The differences between two modes can be really profound and in the RETrigger mode I was able to easily get some odd stuttering rhythms and melodies just by having the LFO rate and TRIGGER be at unrelated, unsynced times. This is easy to do as any incoming trigger will most likely not be in sync [unless your stars magically align] with the LFO rate, though it’s also easy to rectify if you wish to be nice and neat and to sync it all up by using some external time-related CV to control both the LFO rate and the TRIGGER. The second input is the CLOCK, which also has a manual button for setting the clock rate. Patching into the CLOCK [or pushing the manual button] does what the internal LFO rate does, and it’s possible to turn the LFO rate off by turning the knob fully CCW so that the external CLOCK [or button] takes up the clocking job alone. However, the CLOCK, in conjunction with the LFO [which again, can be externally modulated], can create some really unorthodox rhythmic patterns where you can kind of play off each other. Without patching in any CV to overtake the LFO rate, the Clock and LFO rate will be unsynced and that can create random accents and beat additions that are constantly morphing whatever its controlling. I found that I liked the random juicy tidbits that MBE can provide more often kept the LFO rate internal and unsynced from the incoming CLOCK. You can easily sync these up by patching in external CV of familial amounts, if so desired. As for outputs, there are two on MBE; one main OUT that outputs the envelope shapes/bursts, and a GATE out that outputs a gate signal. It’s possible to trigger a burst sequence, thereby illuminating the left LED, only to have no bursts outputted if the LFO rate is off and there is not CLOCK input. To cycle through the burst sequence manually, just hit the manual CLOCK button the requisite number of times [whatever your BURSTS setting is pointing to] to complete a triggered sequence. The left LED will stay lit until the sequence is finished. I found this little exercise somewhat helpful for understanding and remembering what each LED function is, but also how the rate of bursts are generated.
Diving in headfirst, modulating the SLOPE with a square wave LFO at half the rate of the TRIGGER and a sine wave LFO also at half the rate of the TRIGGER to modulate the P-WIDTH so that as the pitch increased, the length of the successive bursts did as well when ascending, and the opposite when descending. You can sync it up for random [but in time, if you so desire] snare accents on a rhythm track, all sorts of melodic or VCA use, and using it on effects like reverb amount and delay feedback was really cool.
Since every parameter on MBE can be CV controlled, you can have them all work together towards a greater in-timed good, or, ummm…not. Sometimes I would patch in a synced up kick [via Noise Reap’s excellent Foundation] to give me a rhythmic backbone in order to make sure my internal mathematic calculations weren’t off, that everything was synced, or just to keep me grounded. Sometimes I felt like I over-patched, over-CV in’ed MBE, with my random, and un-random CVs smothering MBE a bit, but patching it up [with restraint!} and using some of the same exact settings from MBE in a VCO or some other melodic patch and then unpatching that and into a percussive module, as I did with the ADDAC 104, to get some tom sounds [actually, more like cricket chirps in this case] was fruitful, as well using the same settings into both a melodic and percussive patch simultaneously via some mults.
Once I would get a good thing going with MBE it was really cool to gradually increase the P-WIDTH and LFO and listen to the changes in rhythm. If you’re in ONE-SHOT mode and you manually trigger, depending on the settings between the P-WIDTH and LFO it may barely register the number of bursts selected. For example, with the P-WIDTH set at 8, the LFO at 6, the SLOPE fully CCW in the ascending pattern, the number of bursts at 8, and the third envelope shape [the slope-y ramp up shape] selected, it registers basically one long sloping ramp. Change any of the settings, say the envelope setting to the first shape [the hump-y looking one], and you get a slightly curvy set of ramps until the final wave which has the hump slope to it. Changing the P-WIDTH to 4 on this and you get all humps. One highlight while doing this was using the output for panning duties. Panning is one of those things that’s more often than not used a set-and-forget utilitarian type of thing for moving things around to make room and clear space, but using MBE to pan mixed signals created hooks, was addictive, and was in fact was a revelation. Well, two revelations, really. The first revelation; I’m a [now-reformed] lazy panner. The second? Panning can be fun as hell.
There are things about MBE, about the combination of settings, its behaviors and inner-workings which I found impossible to predict, much to my delight. In some instances I knew exactly what would happen if I changed the SLOPE, or increased the LFO rate, but other times I had no idea how a combination of changes would play out, highlighting how much MBE is full of surprises.
So many modules have “tricks up their sleeves”, and of course [eye roll] benefit from “tons of experimenting,” to the point where either of those sayings are usually grounds for deletion in any article, but in the case of MBE, it’s all tricks, all sleeve, all the time, and the experimentation is necessary, fun, and so many times—as I found out over and over—surprising and satisfying. Multi Burst Envelopes [I want to use its formal nomenclature here] is a straight-up gem and raises the bar from just plain ol’ mom and pop everyday ho-hum bursting to something blasting out of the stratosphere, something very much “other” dimensional.

12 HP +12v 28mA -12v 12mA
Price: $289

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